1. Field
The present invention relates to a plasma generating apparatus, and more particularly to a plasma generating apparatus for generating a high-density plasma having superior uniformity.
2. Description of the Related Art
Generally, the plasma is indicative of a highly-ionized gas including positive and negative ions and electrons, and has been widely used for the etching/depositing of the semiconductor fabrication process which forms a fine pattern (e.g., a semiconductor wafer or a glass substrate of the LCD).
Recently, as the integration degree of the semiconductor element gradually increases, a line width of the fine pattern gradually decreases, so that there is needed a plasma generating apparatus capable of generating the high-density plasma to improve the plasma uniformity used for the fine pattern. A variety of plasma generating apparatuses have been widely used, and representative examples are an Inductive Coupled Plasma (ICP) generating apparatus and a Capacitive Coupled Plasma (CCP) generating apparatus. Specifically, in the case of providing the electromagnetic energy for generating the plasma, the ICP generating apparatus has the plasma loss less than that of the CCP generating apparatus, and the sample (e.g., the semiconductor wafer or the glass substrate) of the ICP generating apparatus is not affected by the electromagnetic field, so that the ICP generating apparatus has been used more frequently than the CCP generating apparatus,
Examples of the above-mentioned ICP generating apparatus are shown in FIGS. 1 and 2.
FIG. 1 is a cross-sectional view illustrating a conventional plasma generating apparatus. FIG. 2 is a plan view illustrating a conventional plasma generating apparatus. The plasma generating apparatus of FIG. 1 or 2 includes at least one ferrite core 41.
The conventional plasma generating apparatus 100 includes a vacuum-state upper reaction container 111 and a vacuum-state lower reaction container 112 coupled to each other. The upper and lower reaction containers 111 and 112 include the plasma generated by the ionized injection gas.
The space formed by two reaction containers 111 and 112 is divided into two reaction chambers 113 and 114 by the partitions 121 and 122, respectively. The reaction chambers 113 and 114 include chucks 131 and 132, respectively. The sample (e.g., the semiconductor wafer or the glass substrate) is located at the lower chuck 132. Six toroidal-shaped ferrite cores 141 spaced apart from each other at regular intervals are circularly arranged at the center of each of the reaction chambers 113 and 114. The coil 142 is wound on each ferrite core 141. The coil 142's winding direction among the neighboring ferrite cores 141 are opposite to each other, so that the induced electromotive forces generated from the neighboring ferrite cores 141 have opposite phases.
The reaction chambers 113 and 114 are interconnected via a through-hole 152 formed in the tube 151 passing through the center of the ferrite core 141. The reaction gas passes via the through-hole 152, and the through-hole 152 is used as the path of the discharging current signal. In the case of processing the sample, the coil 142 wound on the ferrite core 141 is used as a primary coil, and the plasma is used as a secondary part, so that the high-frequency RF power applied to the primary coil 142 is applied to the plasma acting as the secondary part. The induced electromotive forces of the neighboring ferrite cores 141 has a phase difference of 180°. The path of the current signal induced to the plasma forms a closed path via two neighboring through-holes 152. The arrows of FIG. 2 indicate six induced current signals formed among the neighboring through-holes 152.
The conventional plasma generating apparatus 100 must configure the path of the secondary current signal induced to the plasma in the form of a closed circuit in order to increase the plasma generation efficiency, so that it requires two reaction chambers 113 and 114. Indeed, the conventional plasma generating apparatus 100 has difficulty in using one of the two reaction chambers 113 and 14, resulting in the loss of plasma and the occurrence of particles.